In an image display apparatus displaying a composite color picture on a display device by mixing a character (letter) picture and a graphic (figure) picture, the existence of color factors (e.g., three primary colors: red, green, blue) constituting each pixel is expressed by a logical value "1", and a nonexistence is expressed by "0", color factors showing a character picture and color factors showing a graphic picture, pixels which corresponding to each other on the pictures are logically summed using logical summation circuits, and the summation is a logical value showing an existence of the color factor of the composite picture. As a result, a superposed composite image of the character picture and the graphic picture is obtained, the character and the graph having colors are superposed, and thus the colors are additively mixed. Since this apparatus uses the logical summation circuits as hardware, an advantage exists of a simple circuit constitution, but a problem arises in that distinction of the character becomes difficult when the character is superposed onto a complicated figure having many colors.